Determination and control of a composition characteristic while blending a multicomponent combustible fluid

ABSTRACT

IN A BLENDING PROCESS WHEREIN A PLURALITY OF COMPONENT FLUIDS IS CONTINUOUSLY INTRODUCED INTO A BLENDING ZONE PRODUCING A COMBUSTIBLE FLUID MIXTURE, A METHOD AND APPARATUS FOR CONTINUOUSLY DETERMINING AND CONTROLLING A COMPOSITION CHARACTERISTIC OF THE COMBUSTIBLE FLUID MIXTURE, SUCH AS THE OCTANE RATING OF A GASOLINE BLEND. A SAMPLE OF THE FLUID MIXTURE IS OXIDIZED IN AN ANALYZER COMPRISING A STABILIZED COOL FLAME GENERATOR WITH A SERVOPOSITIONED FLAME FRONT. THE POSITION OF THE FLAME FRONT IS AUTOMATICALLY DETECTED AND UTILIZED TO MANIPULATE A COMBUSTION PARAMETER IN A MANNER SUFFICIENT TO IMMOBILIZE THE FLAME FRONT REGARDLESS OF FLUCTUATIONS IN COMPOSITION CHARACTERISTIC OF THE FLUID SAMPLE. CHANGES IN COMBUSTION PARAMETER WHICH ARE REQUIRED TO IMMOBILIZE THE FLAME FRONT ARE CORRELATABLE WITH CHANGES IN COMPOSITION CHARACTERISTIC, AND MEANS IS PROVIDED FOR SENSING THE MANIPULATED COMBUSTION PARAMETER AND DEVELOPING THEREFROM A CONDITION OUTPUT SIGNAL WHICH IS FUNCTIONALLY REPRESENTATIVE OF AND CORRELATABLE WITH COMPOSITION CHARACTERISTIC. A SUITABLE REFERENCE FUEL OF KNOWN COMPOSITION CHARACTERISTIC IS PERIODICALLY PASSED TO THE ANALYZER IN PLACE OF THE FLUID SAMPLE, AND MEANS IS PROVIDED TO COMPENSATE THE CONDITION OUTPUT SIGNAL FOR ANY DEVIATION IN THE SIGNAL BETWEEN APPARENT REFERENCE FUEL SIGNAL AND A SIGNAL CORRESPONDING TO THE TRUE KNOWN VALUE OF REFERENCE FUEL COMPOSITION CHARACTERISTIC. MEANS IS ALSO PROVIDED FOR ADJUSTING THE CONDITION OUTPUT SIGNAL RESPONSIVE TO ANALYZER TEMPERATURE FLUCTUATIONS AND COMPONENT CHANGES IN THE BLENDING ZONE. THUS, THE CONDITION OUTPUT SIGNAL IS COMPENSATED FOR COMBUSTION EFFECTS NOT INDICATIVE OF COMPOSITION CHARACTERISTIC, AND IS THEREBY RENDERED FUNCTIONALLY REPRESENTATIVE OF AND CORRELATABLE WITH THE TRUE COMPOSITION CHARACTERISTIC OF THE FLUID SAMPLE OF BLENDED PRODUCT.   D R A W I N G

June l, 1971 E R. FENsKE ETAL y 3,582,281

' DETERMINATION AND CONTROL OF A COMPOSITION CHARACTERISTIC WHILEBLENDING 'A MULTI-COMPONENT COMBUSTIBLE FLUID Filed may 15, 1970 2Sheets-Sheet 1 EMMA,

TTR/VEYS June 1., 1971 E, R, FENSKE ETAL 3,582,281

DETERMINATION AND CONTROL OF A COMPOSITION CHARACTERISTIC WHILE BLENDINGA MULTI-COMPONENT COMBUSTIBLE FLUID Filed May 15, 1970 2 Sheets-Sheet IE//sworfh R. Fens/ra Robert W. Sampson A TTOR/VE YS United States PatentO 3,582,281 DETERMINATION AND CONTROL OF A COMPO- SITION CHARACTERISTICWHILE BLENDING A MULTICOMPONENT COMBUSTIBLE FLUID Ellsworth R. Fenske,Palatine, and Robert W. Sampson,

Arlington Heights, Ill., assignors to Universal Oil Products Company,Des Plaines, Ill.

Filed May 15, 1970, Ser. No. 37,640 Int. Cl. F23m 5 00; G01n 25/46,33/32 U.S. Cl. 23-230 24 Claims ABSTRACT OF THE DISCLOSURE In a blendingprocess wherein a plurality of component fluids is continuouslyintroduced into a blendingzone producing a combustible fluid mixture, amethod and apparatus for continuously determining and controlling acomposition characteristic of the combustible fluid mixture, such as theoctane rating of a gasoline blend. A sample of the fluid mixture isoxidized in an analyzer comprising a stabilized cool flame generatorWith a servopositioned flame front. The position of the flame front isautomatically detected and utilized to manipulate a combustion parameterin a manner sufllcient to immobilize the flame front regardless offluctuations in composition characteristic of the fluid sample. Changesin combustion parameter which are required to immobilize the flame frontare correlatable with changes in-composition characteristic, and meansis provided for sensing the manipulated combustion parameter anddeveloping therefrom a condition output signal which is functionallyrepresentative of and correlatable with composition characteristic. Asuitable reference fuel of known composition characteristic isperiodically passed to the analyzer in place of the fluid sample, andmeans is provided to compensate the condition output signal for anydeviation in the signal between apparent reference fuel signal and asignal corresponding to the true known value of reference fuelcomposition characteristic. Means is also provided for adjusting thecondition output signal responsive to analyzer temperature fluctuationsand component changes in the blending zone. Thus, the condition outputsignal is compensated for com-bustion effects not indicative ofcomposition characteristic, and is thereby rendered functionallyrepresentative of and correlatable with the true compositioncharacteristic of the fluid sample of blended product.

BACKGROUND OF THE INVENTION The present invention relates to a methodand apparatus for determining a composition characteristic of acombustible fluid mixture. It further relates to an improvement in themethod and apparatus for determining a composition characteristic of acombustible fluid mixture utilizing a stabilized cool flame generatorwith a servo-positioned flame front. It particularly relates to animprovement in the method and apparatus for determining a compositioncharacteristic of a combustible fluid mixture produced by blending aplurality of component fluids, and for controlling the blending processto produce a mixture having a constant predetermined value ofcomposition characteristic. It more specifically relates to an improvedmethod and apparatus for determining the octane number of a lgasolineblend produced from a plurality of blending components, and forcontrolling the blending operation to produce a gasoline product ofconstant octane rating.

Those skilled in the art are familiar with the phenomenon of cool flamegeneration. Briefly, when a mixture of hydrocarbon vapor and oxygen at acomposition within the explosion limit is held at conditions of pressureand temperature below the normal ignition point, partial oxida-3,582,281 Patented June 1 1971 tion reactions occur which generallyresult in the formation of by-products, such as aldehydes, carbonmonoxide, and other partially oxidized combustion products. Theseproducts are apparently produced via a chain reaction which, it isbelieved, also produces ions which then in some manner continue thereaction chain. If such a mixture of hydrocarbon vapor and oxygen isisolated and compressed and/ or heated so that these chain reactionsproceed at significant reaction rates, then cool flames are observedwithin the chamber. The cool flames are characterized as light emissionsaccompanied by the evolution of relatively minor amounts of heat.

Implicit in this definition is the fact that the phenomenon of coolflame generation is short of total combustion and short of totalignition and explosion. The work of Barusch and Payne in Industrial andEngineering Chemistry, volume 43, pages 2329-2332, 1951, describes indetail the results which can be obtained from continuous or stabilizedcool flames.

Basically, the utilization of this phenomenon in the practice of thepresent invention is one of manipulating a combustion parameter in amanner sufficient to immobilize the cool llame relative to one end ofthe combustion chamber. The manipulated combustion parameter is sensedand utilized to develop a condition output signal which is functionallyrepresentative of and correlatable with the composition of the fluidbeing oxidized in the combustion chamber.

A more complete explanation and description of the basic apparatus andbasic method for detecting composition characteristics utilizing coolflames is contained in U.S. Pat. 3,463,613, issued on Aug. 26, 1969, toE. R. Penske and I. H. McLaughlin. The contents of said patent areincorporated herein by reference so that a greater detailed discussionneed not be presented in this application. Those skilled in the art arereferred directly to the entire teaching contained in said patent foradditional and specific details as to the construction of a preferredembodiment of the basic apparatus and method of operation thereof. Aswill be more fully developed hereinafter, the present inventiondescribes and claims an improvement in the basic method and apparatusdisclosed and claimed in said patent.

One of the difficulties encountered in the method and apparatusdisclosed in U.S. Pat. 3,463,612, is concerned with calibration of theapparatus to compensate for cornbustion effects which are not indicativeof composition characteristics of the fluid being analyzed.

For example, it has been found that when the apparatus disclosed in theU.S. Pat. 3,463,613 has been operated on a combustible fluid for asubstantial length of time, the apparatus ocassionally begins to producecondition output signals which reflect aging of the apparatus. Thisaging may be introduced due to plugging of preheaters or plugging of aflow diflusor element which is mounted in the interior of the combustionchamber a short Idistance above the combustion nozzle. Additionally, ithas been found that where a leaded gasoline is the cornbustible fluidbeing analyzed, deposits of lead oxides within the combustion chambermay introduce combustion effects which are not indicative of thecomposition characteristic `of the gasoline fraction being burned withinthe chamber.

It has further been discovered that fluctuations in the oxidizer passinginto the combustion chamber will introduce combustion effects which willresult in a condition output signal containing an error which is notcorrelatable with the composition characteristics of the fluid beingburned within the chamber. For example, the typical oxidizer passinginto the combustion chamber is derived from a compressed air system, andthe compressed air will contain microscopic quantities of entrainedlubricating oil which have been picked up at the air compressor.Additionally, it has been found upon occasion that a shift in the winddirection will introduce ue gas from nearby furnace stacks so that theair compressor is periodically picking up air containing combustionproducts. This results in an oxidizer passing into the combustionchamber of the instant analyzer which is not only deficient in oxygen,but which also may contain a considerable proportion of furthercombustible material such as the carbon monoxide and the unburnedhydrocarbons contained in the ue gas.

Furthermore, it is typical in the art to place the com bustion analyzerof the instant invention in a local mounting near the product streamwhich is to be analyzed, and to transmit condition output signalstherefrom to the control house in the refinery or chemical plant whereinthe apparatus is utilized for monitoring or controlling service.Consequently, the combustion chamber of the apparatus is locatedout-of-door and is subject to thermal uctuations due to atmosphericconditions. These fluctuations in atmosperic conditions produce thermaleffects within the combustion chamber which are not indicative of thecomposition characteristic of the fluid being analyzed therein.

Additionally, it is known that the specic nature of the correlationbetween the condition output signal generated by the apparatus and theactual value of composition characteristic is a function of the actualmolecular composition of the fluid being analyzed by the combustionproducing the cool flame. For example, where the uid being analyzedcomprises a hydrocarbon mixture, the correlation between the conditionoutput signal and the composition characteristic will be a function ofthe hydrocarbon fluid composition and the carbon number of thehydrocarbon constituents present therein. Furthermore, the correlationis further influenced by the presence or absence of parafns, isoparains,olefins, diolens, polyoleiins, aromatics, long-chain substitutedaromatics, polynuclear aromatics, etc. Thus, as normally operated incommercial practice, the apparatus of the present invention is capableof continuously analyzing a particular type of hydrocarbon blend orsample fluid, and relatively small deviations due to fluctuations inmolecular species can be accounted for.

However, where the apparatus of the present invention is utilized in ablending process wherein a plurality of component fluids are blendedtogether in varying proportions to produce fluid mixtures of varyingcomposition characteristics, wide fluctuation in the molecular speciescontained within the final mixture may result in combustion effectswhich are not indicative of the true composition characteristic of theresulting blend. For example, in a typical gasoline blending system,blends will be made to produce various qualities of gasoline havingdifferent octane ratings and different volatility characteristics fromseason to season, and even from day to day or hour to hour. Thus where a98 octane rating is desired, the gasoline blend may be high in reformategasoline and thereby highly aromatic, and it will typically contain someantiknock agent such as tetraethyl lead or tetramethyl lead. On theother hand, when a 98 octane rating is desired but reformate gasoline isnot always available in a sufficient quantity, the resulting blend mayperiodically be higher in paraflinic constituents such as straight-rungasoline, and it will then be higher in anti-knock agents. Similarly, atsome periods in the blending operation the gasoline blend may contain asubstantial amount of isoparafnic `gasoline, such as motor alkylate, andat other periods it may contain none. Furtheromer, the apparatus of thepresent invention may be utilized in making more than one `gasolineblend during a given day, each blend meeting a different specication,and composition effects from blend to blend may introduce deviations inthe condition output signal developed by the apparatus which are notactually due to changes in composition characteristic such as octanerating, but which are due to changes in the cornponent distribution ofmolecular species within the blend sampling being burned to produce thestabilized cool flame.

SUMMARY OF THE INVENTION in a stabilized cool flame generator with aservo-posif tioned flame front.

It is a further object of the present invention to provide a method andapparatus for determining a composition characteristic of a combustibleiluid mixture produced by blending a plurality of component fluids, andfor controlling the blending process to produce the mixture at aconstant predetermined value of composition characteristic.

It is a particular object. of the present invention to provide animproved method and apparatus for determining the octane rating of agasoline blend produced from a plurality of blending components, and forcontrolling the blending operation to produce a gasoline blend having aconstant octane rating.

Therefore in its method aspects, a broad embodiment of the presentinvention provides a method for detecting a composition characteristicof a combustible uid mixture produced by combining a plurality ofcomponent uids which comprises: (a) introducing a sample stream of saiduid mixture and a stream of oxygen-containing gas into one end of acombustion zone including an induction section maintained at elevatedtemperature; (b) partially oxidizing said sample stream in saidcombustion zone under conditions sufcient to generate and maintaintherein, a cool flame characterized by a relatively narrow Well-definedflame front spaced from said one end; (c) sensing the position of saidflame front relative to said one end, and developing therefrom a controlsignal; (d) utilizing said control signal to adjust a combustionparameter selected from the group consisting of combustion zonepressure, induction section temperature, sample stream flow rate, andoxygen-containing gas stream flow rate, in a manner sufficient toimmobilize said flame front relative to' said one end regardless ofuctuations in the composition characteristic of said sample stream; (e)sensing the adjusted parameter and developing a parameter signalresponsive to changes in said composition characteristic; (f) developinga component signal representative of the relative amount of a firstcomponent fluid of said plurality contained in said combustible uidmixture; and, (g) passing said parameter signal and said componentsignal into signal conditioning means, and producing therefrom acondition output signal functionally representative of the compositioncharacteristic of said sample stream of fluid mixture, said conditionoutput signal being indicative of said composition characteristic ascorrected for deviations in said parameter signal caused by the relativeamount of said first component fluid in said combustible fluid mixture.

Furthermore, in its method aspects, an additional broad embodiment ofthe present invention provides a method for detecting a compositioncharacteristic of a combustible fluid mixture produced by combining aplurality of component lluids which comprises: (a) introducing a samplestream of said fluid mixture and a stream of oxygen-containing gas intoone end of a combustion zone including an induction section maintainedat elevated temperature; (b) partially oxidizing said sample stream insaid combustion zone under conditions sufficient to generate andmaintain therein, a cool llame characterized by a relatively narrowwell-defined ame front spaced from said one end; (c) sensing theposition of said ame front relative to said one end, and developingtherefrom a control signal; (d) utilizing said control signal to adjust;

a combustion parameter selected from the group consisting of combustionzone pressure, induction section temperature, sample stream flow rate,and oxygen-containing gas stream flow rate, in a manner sullicient toimmobilize said flame front relative to said one end regardless offluctuations in the composition characteristic of said sample stream;(e) sensing the adjusted parameter and developing a first parametersignal responsive to changes in said composition characteristic; (f)developing a first component signal representative of the relativeamount of a first component fluid of said plurality contained in saidcombustible fluid mixture; (g) passing said first parameter signal andsaid first component signal into signal conditioning means, andproducing therefrom a first condition output signal functionallyrepresentative of the composition characteristic of said sample streamof fluid mixture, said condition output signal being indicative of saidcomposition characteristic as corrected for deviations in said parametersignal caused by the relative amount of said first component fluid insaid combustible fluid mixture; (h) periodically isolating said samplestream from said combustion zone, and simultaneously passing a stream ofreference fuel having a known value of composition characteristic, intosaid zone in a manner sufficient to continue the generation of saidimmobilized flame front, (i) sensing the adjusted parameter during theperiod of isolation and passing a second parameter signal into saidsignal conditioning means, said second parameter signal beingfunctionally representative of the apparent composition characteristicof said reference fuel; (fj) comparing said second parameter signal witha reference value of parameter signal functionally corresponding to theactual known value of composition characteristic of said reference fuel;(k) adjusting said signal conditioning means in a manner suilicient toproduce a second condition output signal which is compensated to reflectthe elimination of the difference between 'said second parameter signaland said reference value parameter signal, and which is therebyfunctionally representative of the actual known compositioncharacteristic of said reference fuel; and, (l) periodically isolatingsaid reference fuel stream from said combustion zone while retaining thesignal conditioning adjustment of step (k), and simultaneously passingsaid fluid sample stream into said zone in a manner sufficient tomaintain said flame front, whereby said signal conditioning meansreceives a third parameter signal and a second component signalrepresentative of the relative amount of said first component fluid, andsaid signal conditioning means therefrom develops a third conditionoutput signal compensated for combustion effects not indicative ofcomposition characteristic, and said third condition output signal isthereby functionally representative of the actual compositioncharacteristic of said sample stream.

In addition, in its apparatus aspects, a broad embodiment of the presentinvention provides a composition analyzer for detecting a compositioncharacteristic of a combustible fluid mixture produced by combining aplurality of component fluids, which comprises in combination: (a) acombustion chamber, including an induction section; (b) means forgenerating within said combustion chamber, a cool llame characterized bya relatively narrow Well-defined flame front, utilizing as fuel thereforsaid combustible fluid mixture to be analyzed, said generating meansincluding means passing a stream of said fluid mixture and a stream ofoxidizer into said cornbustion chamber; (c) means sensing the physicalposition of said flame front within said combustion chamber; (d) controlmeans coupled to said position sensing means, and adapted to adjust acombustion parameter selected from the group consisting of combustionpressure, induction section temperatrue, fluid stream flow rate, andoxidizer stream flow rate in a manner suflicient to immobilize saidflame front in a constant physical position relative to said combustionchamber; (e) means sensing the adjusted parameter and developing aparameter output signal which is functio-nally representative of thecomposition characteristic of said fluid stream; (f) means developing acomponent signal representative of the relative amount of a firstcomponent fluid of said plurality contained in said combustible fluidmixture; and, (g) signal conditioning means receiving said parameteroutput signal and said component signal, and producing therefrom acondition output signal which is functionally representative of andcorrelatable with said composition characteristic of the combustiblefluid mixture, said condition output signal being indicative of saidcomposition characteristic as corrected for deviations in said parametersignal caused by the relative amount of said first component fluid insaid combustible fluid mixture.

Still further, in its apparatus aspects, a broad embodiment of thepresent invention provides a composition analyzer for detecting acomposition characteristic of a combustible fluid mixture produced bycombining a plurality of component fluids which comprises incombination: (a) a combustion chamber, including an induction section;(b) means for generating within said combustion chamber, a cool flamecharacterized by `a relatively narrow well-defined llame front,utilizing as fuel therefor said combustible fluid mixture to beanalyzed, said generating means including means passing a stream of saidfluid mixture and a stream of oxidizer into said combustion chamber; (c)means sensing the physical position of said flame front within saidcombustion chamber; (d) control means coupled to said position sensingmeans, and adapted to adjust a combustion parameter selected from thegroup consisting of combustion pressure, induction section temperature,fluid stream flow rate, and oxidizer stream flow rate in a mannersufficient to immobilize said flame front in a constant physicalposition relative to said combustion chamber; (e) means sensing theadjusted parameter and developing a parameter output signal which isfunctionally representative of the composition characteristic of saidfluid stream; (f) means developing a component signal representative ofthe relative amount of a first component fluid of said pluralitycontained in said combustible fluid mixture; (g) signal conditioningmeans receiving said parameter output signal and said component signal;(h) condition signal generating means Within said signal conditioningmeans producing a condition output signal functionally representative ofsaid composition characteristic; (i) means periodically isolating saidfluid stream from said flame generating means, and simultaneouslypassing a stream of reference fuel having a known value of compositioncharacteristic, into said flame generating means in a manner suflicientto continue the generation of said immobilized flame front; (j) meanspassing to said signal conditioning means, a timing signal indicative ofthe passage of reference fuel to said flame generating means; (k)comparison means within said signal conditioning means, responsive tosaid timing signal, adapted to compare the condition output signalgenerated due to reference fuel flame front with a reference valuesignal functionally corresponding to the actual known value ofcomposition characteristic of said reference fuel, and therefromdeveloping a comparison signal; (l) adjusting means within said signalconditioning means, responsive to said comparison signal, and adapted toadjust said condition signal generating means to compensate fordeviations between the condition output signal generated due toreference fuel flame front and said reference value signal; and, (m)means for retaining said adjustment to said condition signal generatingmeans when said isolation period is ended and said fluid stream isreturned to said flame generating means in place of said reference fuel,`whereby the condition output signal generated by said fluid streamflame front is compensated for combustion effects not indicative ofcomposition characteristic, yand said condition output signal is therebyfunctionally representative of and correlatable with the actualcomposition characteristic of said combustible fluid mixture.

In essence therefore, the present invention provides a method andapparatus which determines the composition characteristic of acombustible fluid mixture by oxidizing the lluid in a stabilized coolflame generator with a servoposition flame front to develop a conditionoutput signal which is compensated for fluctuations in the relativeproportion of component fluids passing into the blending system whichproduces the mixture, and which is periodically recalibrated tocompensate for deviations in condition output signal generated by areference fuel of known composition characteristic. Furthermore as shallbe set forth hereinafter, the condition output signal is compensated fortemperature fluctuations occurring within the inventive apparatus. Inthis manner then, the condition output signal is continuouslycompensated for combustion effects which are not indicative ofcomposition characteristic, and the condition output signal is therebyrendered functionally representative of and correlatable with the truecomposition characteristic of the combustible fluid blend beinganalyzed. Thus as shall be set forth more fully hereinafter, theapparatus of the present in- .vention is readily adaptable forcontrolling the blending process to produce a final product having aconstant predetermined value of composition characteristic, such asoctane number in a gasoline blending operation.

As used herein, the term composition characteristic does not refer to acompound by compound analysis of the type presented by instruments suchas mass spectrometers or vapor phase chromatographs. Rather, thecomposition characteristic is represented by a continuous, orsubstantially continuous, output signal which is responsive to andindicative of the fluid composition, and which is more specifically,empirically correlatable with one or more conventional compositionidentifications or specifications. For example, when the `fluid to beanalyzed is a. hydrocarbon composition, the composition characteristicwhich is represented by the condition output signal may be aconventional identification or specification such as the Reid VaporPressure, ASTM or Engler distillation, initial boiling point, endboiling point, etc. In particular, when the lluid being analyzedcomprises gasoline boiling range hydrocarbon, the compositioncharacteristic which is functionally represented by the condition outputsignal will typically comprise a knock characteristic such as researchoctane number or motor octane number.

As used herein, the terms output signal, condition output signal andparameter signal are to be construed in their most meaningful sense andinclude analog signals of all types, such as amplitude-modulated,phasemodulated, or frequency-modulated electrical signal or pressuresignals by conventional pneumatic transmission media, as well as digitalrepresentations thereof. These terms are further intended to includesimple mechanical motion or displacement of a transducer member (whetheror not mechanically, electrically, or pneumatically coupled to aphysical display means, such as an indicating arm, recorder pin, ordigital display board) includin-g by way of illustration, the expansionor contraction of a Bourbon tube, pressure spiral or helix, thedisplacement of a bellows-dapper, nozzle-diaphragm, or differentialtransformer-core assembly, the movement of a bimetallic temperatureresponsive element, the motion of a slider of a self-balancingpotentiometer, etc.

The condition output signal may be transmitted without physical displaydirectly to reset a nal control unit, such as a diaphragm motor valve ora sub-control loop in a cascade system. More commonly, however, thecondition output signal will pass to a readout device which willcomprise or will be coupled to an indicating or recording means, thescale or chart of which may be calibrated in terms of the desiredidentifying composition characteristic of the fluid sample, such asoctane num- `8 ber, initial boiling point, 90% boiling point, vaporpressure, and the like.

In the practice of this invention the location of the cool flame frontis, preferably, determined by temperature sensing devices, such as apair of axially spaced thermocouples fixed at a known distance from oneend of the combustion zone and at a known and fixed distance from eachother, e.g. one (l) inch. As will be more fully developed hereinbelow,the signal developed by the thermocouple means activates appropriatecontrol means for adjusting a combustion zone parameter or condition soas to immobilize the cool llame front at a position generally betweenthe two spaced thermocouples. A most satisfactory combustion conditionwhich can be used as the control means is the combustion zone pressure.

Test samples which can be continuously analyzed by this inventioninclude normally gaseous and normally liquid combustible chemicals. In aparticularly preferred embodiment, the test samples comprisehydrocarbon-containing mixtures. These mixtures typically comprise atleast one hydrocarbon containing from 1 to about 22 carbon atoms permolecule in admixture with one or more non-hydrocarbons such ashydrogen, nitrogen, carbon monoxide, carbon dioxide, water, and hydrogensulfide. Alternatively, these mixtures will comprise at least twodifferent hydrocarbons containing from 1 to about 22 carbon atoms permolecule. The upper limit on carbon number is xed generally by thepreferred operational procedure whereby the test sample and thereference fuel sample are vaporized in an air stream under combustionconditions without undergoing any substantial thermal decompositionprior to the oxidation thereof.

Therefore, in the context of the present invention, the termscombustible fluid mixture and combustible fluid are intended to embodyall fOrms of combustible fluids which are capable of vaporization withinthe apparatus, and particularly hydrocarbon mixtures in whichhydrocarbons predominate, but which may also contain significant amountsof non-hydrocarbon materials. In particular, the hydrocarbon fluids maycontain such items as tetraethyl lead, tetramethyl lead, and other knownanti-knock compounds for use in motor fuel compositions. In thepreferred and practical embodiment of this invention, wherein thedetermined, composition characteristic is the measurement of octanerating, the feedstocks or test samples of unknown octane number whichare chargeable to the apparatus of the present invention include thosewithin the gasoline boiling range produced by blending such componentfluids as straight-run gasoline, cracked gasoline, motor alkylate,catalytically reformed gasoline, thermally reformed gasoline,hydrocracker gasoline, etc.

As noted hereinabove, the apparatus of the present invention will becontinuously recalibrated and compensated for combustion effects Whichare not indicative of the composition of the fluid being analyzed or ofthe composition characteristic being developed as the condition outputsignal. In order to achieve this compensation in the condition outputsignal, there is provided means for periodically isolating the blendedfluid being tested from the combustion chamber of the apparatus, and forsimultaneously introducing therein a sample of a reference fuel. Thoseskilled in the art are familiar with the procedures for obtainingreference fuels of known composition. Since vthe reference fuel is beingcompared to the unknown blended fluid, it is desirable that thehydrocarbon species of the reference fuel be similar to those of theunknown fluid being tested. Thus for example, if the iluid beinganalyzed is a hydrocarbon comprising a gasoline blend having an octanenumber of about 95 and consisting primarily of a reformate gasoline, itis particularly desirable, but not essential, that the reference fuelalso have an octane rating of about 95 and that it primarily comprise areformate gasoline.

The oxidizer or oxidizing agent utilized in the apparatus of the presentinvention is preferably an oxygen-containing gas, such as air,substantially pure oxygen, etc. or it may be a synthetic blend of oxygenwith an inert or equilibrium effecting diluent, such as nitrogen, carbondioxide or steam.

'Ille generation of the stabilized cool flame is effected undercombustion conditions generally including superatmospheric pressure andelevated temperature, although in some cases, it may be desirable to useatmospheric pressure or sub-atmospheric pressure. For example, thepressure may be in the range from about 15 p.s.i.a. to about 165p.s.i.a. with a maximum flame front temperature in the range of 600 F.to l000 F. For measuring the composition of a gasoline boiling rangefraction it iS preferable to employ pressures in the range from 16p.s.i.a. to 65 p.s.i.a., more preferably, in the range from 16 p.s.i.a.to 30 p.s.i.a., together with an induction zone temperature of fromabout 550 F. to about 850 F. Control of induction zone temperature canbe effected by the amount of preheat imparted to the air or oxidizerstream and to the incoming sample stream, including the test sample andthe reference sample. Furthermore, induction zone temperature may bemanipulated by adjusting the input of heat from an external source tothe combustion zone proper. In any case, the permissible limits withinwhich temperature and pressure may be individually varied withoutdeparture from stable operation, even outside of the specificoperational limits referred to herein, can be determined by simpleexperiment for a particular type and quantity of combustible fluidsample.

As previously mentioned, the detection o the position within thecombustion chamber for the test sample and for the reference sample ispreferably effected by temperature responsive thermoelectrical means,although, other equivalent means can be used. The thermocouple sensingdevice may be placed within the combustion chambers, as discussedhereinabove, or outside of the combustion chamber, and may be eitherfixed or may be movable in such a manner as to completely andsubstantially traverse the length-wise direction of the combustionchamber in order to locate the position of the stabilized cool flamewithin the combustion chamber.

The output signal from the thermocouple sensing means is fed throughsignal means to suitable control means such as a motor activated controlvalve for regulating, perferably, the pressure within the combustionzone. Generally, the output signal from the thermocouple sensing meansis not sent to a readout device, such as a strip chart or x-y recorder,for to do so would deplete the strength of the signal to such an extentthat operational efficiency might be impaired. Preferably, thethermocouple sensing device comprises a pair of axially spacedthermocouple leads which are inserted into thin-walled thermal typepencil wells and may be constructed of any materials known to thoseskilled in the art, such as for example, iron-constantan. The lead wiresfrom the thermowells are connected -to a suitable `differentialtemperature controller. Such controller may be a conventionalselfbalaucing potentionmeter in combination with pneumatic controlmeans. A suitable input span for the controller may be from to +5milivolts and the output signal thereof transmitted may 'be aconventional 3-15 p.s.i.a. air signal. This control signal is used, forexample, to reset the set point on a back pressure controller or can beused to directly control the pressure Within `the combustion zone.

The present invention may be more fully understood by now referring tothe accompanying drawings.

FIG. l comprises a simplified schematic representation of the apparatusfor practicing the present invention in a typical gasoline blendingsystem wherein the signal conditioning means is a computer means, whichmay be an analog computer or a digital computer.

FIG. 2 illustrates a schematic representation of the apparatus forpracticing the present invention in a typical 10 gasoline blendingsystem wherein the signal conditioning means comprises an analog or adigital network.

DESCRIPTION 0F THE DRAWINGS With reference now #to the accompanying FIG.l, there is shown the apparatus of the present invention which comprisesin combination a canister 1 enclosing a combustion cham-ber 2. TheIcanister has means for lintroducing a heat transfer fluid to surroundthe combustion chamber so that proper temperature conditions may bemaintained within the combustion zone, by controlling temperature in anelevated temperature zone 3 which is confined between the canister 1 andthe combustion chamber 2. The configuration of the apparatus will besimilar to that described in the cited U.S. Pat. 3,463,613. Thus thetemperature within the elevated temperature zone 3 may be maintained bya constant circulation of a heat transfer fluid from an external source,or by conduction and natural convection of the heat transfer fluid asprovided by immersion heaters contained within the canister and withinthe zone 3, or heating elements encompassing the canister. If desired,the exterior of `the enclosing canister 1 may be encased in one or morelayers of insulation, not shown, and typically this will be done `sincethe canister is normally located out-of-doors and exposed to atmosphericconditions. Those skilled in the art being familiar with the -teachingspresented herein and with the teachings presented in the cited patentwill understand the appropriate manner of enclosing the cornbustionchamber in a suitable canister having appropriate temperature controlmeans and having appropriate thermal insulation in order to minimize thethermal effects of atmospheric conditions.

With reference to the combustion chamber 2, there is providedtemperature sensing means 4 and 5 which are capable of sensing thelocation of the stabilized cool flame front generated within thecombustion chamber by the oxidation of the sample being introducedtherein. The combustion chamber 2. is provided with inlet means 6 whichintroduces a mixture of air, or other oxidizing agent, and a combustiblefuel into a burner nozzle, not shown, contained within the lower sectionof the combustion chamber 2. The air or oxidizing agent is introducedinto the system via line 8 and the combustible fluid s introduced intothe system via line 7. The net combustion products are ultimatelydischarged from the combustion chamber via line 9.

The mixture of air and combustible fluid passes into the chamber 2 vialine 6 wherein it is ignited due to the elevated temperature. The regionof the combustion chamber 2 which is located between the inlet line 6and the temperature sensing means 5 is known as the induction section.The induction section is defined as that portion of the combustion zonewherein oxidation of the combustible fluid is initiated. Therefore theinduction section more particularly comprises that portion of thecombustion chamber 2 located between the lburner nozzle and the coolflame front which is generated by the combustion.

In a preferred embodiment of the present invention, the apparatus shownin the yattached FIG. 1 is utilized to detect the octane number of agasoline blend of unknown composition. The gasoline fraction isintroduced into the analytical system via line 19 from a gasolineblending process which will be described more fully hereinaf-ter. Asample of blend is passed via line 19 through control means 21, and thesample then enters line 7 wherein it is contacted with a stream of airpassing into the system via line 8. The air and the gasoline sample passinto the combustion chamber 2 via line 6. 'Ihe mixture of air andgasoline passes through the -burner nozzle at the bottom of chamber 2,not shown, and enters the induction section of the combustion chamber.The temperature of the induction section is about 630 F. and ismaintained thereat by the heated fluid medium which completely surroundsthe combustion chamber in the elevated temperature zone 3. The oxygenand the -gasoline react within the induction section producing anexothermic reaction resulting finally in a temperature elevation to apeak of about 750 F., whereat there is developed a cool flame front. Atthis point, the temperature of the combustion mixture falls off rapidlyto about 640 F. When the cool flame front is stabilized, the temperaturesensing means 4 and 5 will sense an identical temperature due to thefact that the combustion produces a peak temperature with a rapidtailing off of temperature. The exhaust gases from the combustion thenleave the `cornbustion chamber 2 via line 9- With reference to thecombustion parameter which is manipulated and adjusted in order tostabilize or immobilize the cool flame front between temperature sensingmeans 4 and 5, the preferred embodiment is to adjust the pressure withinthe combustion zone, as was previously mentioned hereinabove. In otherwords, an increase in pressure will cause the flame front to recedetowards the burner end of combustion chamber and a decrease in pressurewill cause the flame front to advance away from the Iburner end of thechamber and more closely approach the discharge end thereof. Therefore,if the flame front attempts to move toward the burner end of thechamber, the temperature sensing means 5 will reflect a temperaturerise. Temperature sensing means 5 will reflect a temperature rise.Temperature sensing means 4 and 5 will transmit the sensed temperaturesvia transmitting means and 11 to a differential temperature controller12, which will then activate a pressure controller 14 by passing apressure control signal thereto via line 13. The pressure controllerwill be activated in order to decrease combustion pressure until theflame front is restored to its original position between the axiallyspaced temperature sensing means 4 and 5. Conversely, if the hydrocarboncomposition changes so that the flame front attempts to move away fromthe burner end of the chamber, temperature sensing element 4 will sensea temperature rise and the differential temperature controller willactivate the pressure controller 14 to increase combustion chamberpressure until the front is restored to the original position.

Although the preferred embodiment of the invention comprises themanipulation of pressure as the controlled combustion parameter, othercombustion conditions may be adjusted, with equally satisfactoryresults, in a manner sufficient to immobilize the flame front to aconstant position lwithin the combustion chamber. Thus, as disclosed inthe cited U.S. Pat. 3,463,613, a combustion parameter which may beadjusted by the control signal 13 from the differential temperaturecontroller 12 includes the hydrocarbon sample flow rate in line 7, theoxygen containing gas flow rate in line 8, and the induction zonetemperature. In either case, regardless of which combustion conditionparameter is manipulated, the apparatus operates with the selectedcombustion parameter being adjusted lin a manner to immobilize the flamefront relative to its position within the combustion chamber 2,regardless of changes in the test sample composition. Thus thecombustion parameter is sensed and utilized to develop an output signalwhich is then indicative of the composition characteristic of thecombustible fluid being analyzed, which in a preferred embodiment is theoctane number of a gasoline sample.

The temperature sensing means for determining the location of 'thestabilized cool flame is preferably a thermalelectric means such as apair of axially spaced thermocouples 4 and 5. However, other means fordetermining the flame position will be apparent to those skilled in thecontrol arts and are deemed embraced in the broad scope of thisinvention. For example, one may employ spaced resistance bulbs or simplya pair of spaced resistance wires stretched tightly across thecombustion zone, connected in a standard bridge circuit, instead of thepreviously described thermalelectric elements. Alternatively,

optical-electric means, such as radiation pyrometers may be used. Sincethe flame front contains an appreciable concentration of organicradicals and ions, its position may also be detected by ion sensitivemeans such as a capacitor in the tank circuit of a high frequencyoscillator whereby linear displacement of the flame will change thedielectric constant of the capacitor and hence, the resonancecharacteristic of the oscillator. Or the flame region may comprise adirect-current ionization gap. Those skilled in the art may readilydetermine the appropriate sensing means for determining the position ofthe stabilized cool flame in the combustion zone of the presentinvention.

In -a preferred embodiment of the inventive apparatus, the cool flamefront for the combustible fluid sample is positioned between la pair ofthermocouples 4 and 5 placed in the combustion zone. Both thermocoupleswill be at about the same temperature and the voltage appearing at theinput of the differential temperature controller 12 will beapproximately zero. However, equally satisfactory operation can beachieved by having a net voltage difference if the positive or negativecorresponding to a temperature differential is .in the order of 10 F. to40 F. This means that the flame front in the combustion chamber 2 isthen slightly asymmetrical with respect to the thermocouples 4 and 5.While this mode `achieves greater sensitivity, it is not a criticalrequirement and one may still get good results with the apparatus if azero temperature differential is maintained within the device 12.

In any event, the sensing means 4 `and 5, the transmitting means 10 and11, :and the differential temperature controller 12 will enable one todetermine the exact position of the cool flame front by a differentialtemperature measurement. Controller 12 will then activate the pressurecontrol means 14 4in order to ladjust the flame front :to a positionwhere there is, as previously mentioned, typically a zero temperaturedifferential. Therefore, the change in combustion pressure which isrequired to immobilize the flame front in its predetermined location, isa correlatable function with the composition of the fuel which is beingoxidized within the combustion chamber 2.

Accordingly, then, there is provided within the apparatus a pressuresensing means 15 which develops a continuous pressure signal transmittedvia line 1'6 to a transducer 17. The transducer 17 converts thepneumatic or mechanical pressure signal 16 into an electrical signalwhich may be a voltage signal or an amperage signal. The transducer 17transmits a converted parameter output signal via line 18 into a signalconditioning means 25, which in this embodiment comprises a digital oran analog computer means. Computer means 25 contains an internalcomputer program by which the converted parameter signal 18 iscontinuously converted into a pair of output signals 26 and 84, whichare functionally representative of and correlatable with the octanerating of the combustible sample of gasoline `blend introduced into thesystem via line 1'9. The condition output signal 26, typically, isthereupon transmitted to an octane display device 27 which may comprisea recording chart device, or a tape print-out device, or any other typeof indicating means. In addition, the octane display device 27 maycomprise a control system whereby an output signal for control of octanenumber is transmitted to means 85, to be discussed hereafter, forcontrolling the octane rating of the blend which provides the testsample entering via line 19. However, in the embodiment of FIG. 1,control means is adjusted by condition output signal 84.

As previously noted, the apparatus of the present invention is typicallylocated out-of-doors. Accordingly, it is subject to combustion effectscreated by changes in atmospheric conditions. In order to compensate forchanging atmospheric conditions, there is provided within the apparatusof the present invention a temperature sensing means 28 which is capableof sensing any fluctuations in temperature Awithin the elevatedtemperature Zone 3.

Alternatively, temperature sensing means 28 may be positioned withincombustion chamber 2 in order to sense actual uctuations in inductionsection temperature. Temperature sensing means 28 passes a temperatureoutput signal via transmitting means 29 to the signal conditioning means25. The internal program of the computer means 25 thereupon makes atemperature correction to the condition output signals passing via lines26 and 84. Thus, the octane value thereafter indicated by octane displaydevice 27 is continuously compensated for any error in the indicatedcomposition characteristic which is due to temperature fluctuations inthe induction section of chamber 2 or in the elevated temperature zone3, caused by changes in atmospheric conditions.

In addition, the method and apparatus of the present invention providesfor a continuous compensating adjustment to condition output signals 26and 84 which reflects and compensates for fluctuations in the relativeproportion of the various component uids which are entering the blendingsystem to produce the finish blend, a test sample of which is passedinto the apparatus via line 19.

Referring again to FIG. 1, there is shown a typical blending systemwherein a plurality of gasoline blending components are passed into ablending zone to produce a nished blended gasoline having apredetermined composition characteristic, such as octane rating. Areformate gasoline stream enters the. blending process via line 40 and astraight-run gasoline stream enters line 40 via line 41. Typically, thegasoline blending system will blend at least two component gasolines,but for illustrative purposes various component gasoline fractions areshown in FIG. l, inv order to illustrate the various types ofhydrocarbon constituents which may be blended together. Thus, there isshown in FIG. l an alkylate gasoline fraction entering line 40 via line42, a cracked gasoline fraction entering line 40 via line 43, avolatility component such as butane and/or pentane entering line 40l vialine 44, and an anti-knock agent such as a lead alkyl entering line 40via line 45.

The reformate gasoline fraction is a highly aromatic stock, while thestraight-run gasoline fraction is a blending component which is high innormal paraiiins and in naphthenes. The alkylate gasoline fraction is ablending component which is high in isoparaiins, while the crackedgasoline fraction is a stock which is high in olefins. Therefore, therelative amount of each component passing into the blend, andfluctuations thereof, will produce individual combustion eects in theanalyzer of the present invention which introduce deviations in thecondition output signal which are not indicative of the blendedcomposition characteristic being determined.

The combination of blending components passes via line 40 into a mixingor blending zone, which for illustrative purposes is shown in FIG. l asan in-line blender 46. The inal gasoline blend is discharged fromin-line blender 46 via line 47 and a sample of the linished blend iswithdrawn via line 19 as discussed hereinabove.

In order to make compensating adjustments to the condition outputsignals 26 and 84 which are reflective of the varying proportions ofcomponents passing into the blending process, there is provided meansfor sensing the flow of each component fluid passing into the blendingsystem. In order to sense the flow of reformategasoline, there isprovided in line 40 a ow sensing means such as an orifice 48 whichtransmits a flow signal via line 49 to a transducer 50. The differentialpressure signal developed by the iiuid passing through orilice 48 andtransmitted via line 49, is converted by transducer 50` into anelectrical signal which is passed via line 51 into the computer means25. The flow of straight-run gasoline is sensed by a flow sensing means54 which transmits a AP flow signal via line 55 to transducer 56, whichthereafter passes an electrical flow signal via line 57 into computermeans 25. In a similar manner, the rate of ow of alkylate gasoline intothe blending process is sensed by orifice 60 which transmits a AP owsignal via means 61 to transducer 62, which in turn transmits anelectrical ow signal to computer means 25 via line '63. Additionally,the cracked gasoline ow rate is sensed and transmitted by means 66, 67,68, and 69 to deliver an electrical input signal of cracked gasoline owto computer means 25. The volatility component flow is sensed andtransmitted by means 72, 73, 74, and 75 to deliver an electrical flowsignal of volatility component to computer means 25. Finally, the flowrate of lead alkyl entering the blending process is sensed andtransmitted by means 78, 79, and 81, whereby an electrical flow signalis delivered to computer means 25.

Computer means 25, now continuously receiving the rate of ow for eachcomponent entering the blending process, takes the information into theinternal program of the computer, whereby the relative inuence of eachcomponent upon the combustion within the combustion chamber 2 isdetermined. In this manner, the relative' rate of iiow of each componentprovides a direct measurement of the relative combustion effect of thearomatic component entering the process, the normal paraffnic componententering the process, the naphthenic component entering the process, theisoparaflinic component entering the process, the olelinic componententering the process, the volatility component enteringthe process, andthe anti-knock agent entering the process. Cornputer means 25 is able bymeans of the internal computer program, to make compensating adjustmentsto the parameter input signal 18, and thereby render a correction to theresulting condition output signals 26 and 84 which reflect a correctionto these output signals for the effects of the various componentsentering the gasoline blend.

Thus, condition output signals 216 and 84 are conltinuously compensatedfor combustion effects which are not indicative 0f the compositioncharacteristic being determined, such as blend octane rating.

As noted hereinabove, the signal conditioning means 25 delivers acondition output signal via transmitting means 84 to a controllingmeans, which for illustrative purposes is shown as a valve means 85located in line 45. In this manner, then, the computer means 25 willadjust the input flow of one or more components entering the blendingprocess, whereby the condition output signal generated by the analyticalapparatus of the present invention is utilized to control the blendingsystem in a manner suicient to produce a constant value of compositioncharacteristic for the final flinished blend product. As notedhereinabove, in the preferred embodiment of the present invention, theblending process wherein the apparatus of the present invention isutilized is a gasoline blending process. Accordingly, therefore, it ispreferable that the condition output signal 84 and the control means 85be utilized to control the input of at least one high octane blendingcomponent such as the reformate gasoline entering the blending systemvia line 40, or to control the input of an anti-knock agent such as thelead alkyl entering the blending system via line 45. Alternatively, theinput of a low octane component such as the straightrun gasoline couldbe controlled. In this manner, then, the apparatus and control systemwill produce a controlled nished gasoline blend which has a constantoctane rating in accordance with the specification which is set for thegiven blend which is being produced and analyzed.

In addition, the apparatus of the present invention provides for arecalibration or a re-izeroing of the system for deviations created byother combustion eects which are not reflective of the compositioncharacteristic of the blended fuel being tested. Accordingly, there isprovided means for periodically passing into the combustion chamber 2 areference fuel by which the system may be recalibrated.

Thus, there is shown in FIG. 1 a reference fuel passing into the systemvia line 20. A timing device 23 passes a timing signal via line 22 intoa control valve 21. During the period of isolation, the control valve 21receives a timing signal by which the test sample of line 19 is switchedout of the system and the reference fuel of line 20 is switched into thesystem. Thereafter, during the isolation or reference period, referencefuel passes via line 7 into line 6 in admixture with the air enteringvia line 8.

The reference fuel produces a stabilized cool flame which is indicativeof the octane rating, or other composition characteristic beingdetermined, of the reference fuel. The temperature sensing means 4 and 5transmit the sensed temperature signals via means 10 and 11 into thedifferential temperature controller 12, whereupon differentialtemperature controller 12 passes a control signal via line 13 topressure control means 14. The pressure sensing means 15 passes thepressure signal via line 16 into transducer 17 which in turn passes aconverted parameter sig-nal |18 into the computer means 25. The internalprogram of computer means 25 compares the signal 18 with a referencesignal contained within the program. The reference signal is indicativeof the known actual octane rating of the reference fuel. The timingdevice 23 sends a signal via line 24 to the computer means 25 duringthose periods of time when the reference fuel is being burned withincombustion chamber 2.

Accordingly, then, the computer program Will make a compensatingadjustment to the condition output signal 26 in order to eliminate anydeviation of converted parameter signal 18 from the known signal whichis reflective of the actual composition characteristic or octane numberof the reference fuel. When the period of isolation is ended, timer 23sends a signal via line 22 to valve 21 to swing the valve in a mannersufficient to isolate the reference fuel of line from the system and tocontinue the introduction of test sample via line 19. At this pointthen, the timing signal passing via line 24 to computer means 25,informs the computer means that the reference fuel has been cut out ofthe system and that the test sample has been reintroduced. The internalcomputer program of the computer means 25 at this point retains anyreference fuel correction which was made within the system.Consequently, the resulting condition output signal passing via line 26to octane display device 27 when the test sample is being tested, willreflect a cornpensation or recalibration of the system for the referencefuel.

Of course, those skilled in the art will readily perceive that duringthe isolation or reference period when the test sample of line 19 isreplaced by the reference fuel of line 20, the condition output signall84 cannot be utilized to control the valve means 85 and therebymaintain a constant predetermined value of octane rating for theiinished blend. During this isolation period the converted parametersignal 18 passing into the signal conditioning means 25 will not beindicative of the composition characteristic of the finished blend sincethe signal 18 is produced by the combustion of the reference fuel.Accordingly therefore, when the timing signal 24 which passes into thecomputer means 25 relates to the internal program that reference fuel ispassing into the combustion chamber 2, the internal program of computermeans 25 will provide that the condition output signal 84 will be lockedin, so that the valve means 85 will be held at a constant throttlingposition. Therefore, during the short period of recalibration or ofre-zeroing the apparatus of the present invention to compensate foraging effects in the combustion tube as indicated by the combustion ofthe reference fuel, the finished blend will be produced at a constantpredetermined octane rating in accordance with the last setting whichwas provided by the combustion of the test sample.

Accordingly then, when the timing device 23 again cuts the test sampleof line 19 back into the apparatus of the present invention andsimultaneously isolates the preference fuel of line 20 therefrom, theindicated octane num- 16 ber of the test sample which is thereafterproduced during the testing period Will have been corrected forcomponent proportions, for temperature conditions, and for othercombustion effects which were not truly indicative of the compositioncharacteristic such as octane number. Accordingly then, the indicatingcondition output signal 26, as well as the controlling condition outputsignal 84, will be truly indicative of and directly correlatable withthe octane number or other composition characteristic of the test samplebeing oxidized .in combustion chamber 2.

Referring now to FIG. 2, there is shown a second embodiment of thepresent invention wherein the signal conditioning means of FIG. 1, thecomputer means 25 and its internally contained program, is replaced by asignal conditioning means preferably comprising a network of analogelements, although a network of digital elements may be used. The basicelements of the analytical apparatus and the blending system which aredisclosed in FIG. l, are again illustrated in FIG. 2.

In the embodiment of FIG. 2, however, the transducer output signalleaving transducer 17 is transmitted via means 18 into a signalconditioning network 30. The signal conditioning network 30 is a type ofapparatus which is well known in the art. The converted parameter signal18 passing from transducer 17 has a fixed correlation between thepressure which is sensed in the combustion chamber 2 by the pressuresensing means 15, and the resulting electrical output signal which ispassed through the signaling conditioning network The conditioningnetwork 30 either multiplies, or it adds and subtracts to the receivedtransducer signal 18 in order to produce a net output signal which iscorrelatable with octane rating or any other composition characteristicbeing determined. In the preferred embodiment, signal conditioningnetwork 30 will add and subtract to the signal 18. The resultingpressure output signal is transmitted from signal conditioning network30 via transmitting means 31 into a summing means 32.

In addition, in the embodiment illustrated in FIG. 2, the temperaturesignal which is sensed in the elevated temperature zone 3 by the sensingmeans 28 is transmitted via line 2 9 into a signal conditioning network33. Again, the signal conditioning network 33 is a type of network whichis well known in the art. The temperature signal has a fixed correlationbetween the temperature in the elevated temperature zone 3 and theoctane rating or other composition characteristic being determinedwithin the combustion chamber 2. The conditioning network 33, therefore,adds or subtracts to the signal 29 in a manner suicient to compensatefor any temperature deviations from a fixed temperature which is thestandard base temperature for the elevated temperature zone 3.Alternatively, induction section temperature may be sensed by means 28,and network 33 may compensate for any deviation from the base inductionsection temperature. The resulting signal is passed from the signalconditioning network 33 with a compensation for any temperaturedeviation, into summing means 32 via transmitting means 34.

Furthermore, in the embodiment of FIG. 2, the converted flow signal 51which is representative of the flow of reformate gasoline passing intothe blending process, is transmitted to a signal conditioning network52. Again the signal conditioning network 52 is a type of network whichis well known in the art. There is a fixed correlation between theactual ilow of the reformate` gasoline and the resulting octanecontribution to the final blended gasoline product octane number.Consequently, the signal conditioning network 52 develops a continuousoctane correction factor for the flow of aromatic fluid passing throughorifice 48. The aromatic or reformate octane correction factor is pasedvia transmitting means 53 to summing means 32.

In a similar manner, there is a provision for 4passing the convertedflow signal 57, which is representative of the flow of straight-rungasoline into the blending process, to a signal conditioning network 58.This signal conditioning network is similar to that of network 52. Thereis a fixed correlation between the actual flow of the straight-rungasoline and the resulting octane contribution of the straight-rungasoline to the final blended gasoline product octane number.Consequently, signal conditioning network 58 develops a continuousoctane correction factor for the flow of this normal paraffinic fiuidpassing through the orifice 54. This normal parafiinic or straight-rungasoline octane correction factor is transmitted via means 59 to thesumming means 32.

In a similar manner, the alkylate gasoline component flow signal 63 ispassed to a signal conditioning network 64 which develops an octanecorrection factor for the isoparafiinic component passing to thegasoline blend. The octane correction factor is passed from signalconditioning means 64 via transmitting means 65 to the summing means 32.

A correction to the octane contribution of the cracked gasoline is alsoprovided for in the apparatus as set forth in FIG. 2. Flow signal 69passes into a signal conditioning network 70 which thereafter transmitsan octane correction factor for the olefnic component via transmittingmeans 71 into the summing means 32. Similarly, a correction for theoctane contribution of the volatility component is provided by sendingthe flow signal 75 to a signal conditioning network 76 which thereupondevelops an octane correction factor signal passing via means 77 to thesumming means 32. Finally there is indicated in FIG. 2, an octanecorrection for the lead alkyl component passing into the blendingprocess. This is provided by sending the anti-knock agent flow signal 81into the signal conditioning network 82 `which in turn develops anoctane correction factor transmitted via means 83 to the summing means32.

Summing means 32 receiving the temperature signal 34, the parameteroutput signal 31, and the component octane correction factor signals 53,59, 65, 71, 77, and 83, thereupon algebraically sums the signals. Thenet result of the algebraic summation accomplished by summing means 32is a modified parameter signal fwhich is in fact the net conditionoutput signal which is indicative of the apparent compositioncharacteristic as compensated for any component and temperaturefluctuations. Thus when the test sample of line 19 is oxidized incombustion chamber 2, the summing means 32 sends a condition outputsignal 26 to the octane display device 27 which gives the apparentoctane rating of the test sample of the finished blended gasolineproduct.

In the embodiment illustrated in FIG. 2, the octane display device 27contains a control system Iwhich not only gives an indication of theactual octane of the test sample but which also develops a controloutput signal 86 passing to the control valve 85. The control set pointcontained within means 27 is set to the desired specificationcomposition characteristic, in this instance the octane rating of thefinished blend, and the control output 86 thereupon throttles the valve85 to admit a sufficient amount of anti-knock agent (lead alkyl) tocontrol the octane rating of the finished blend to the specification setpoint. Of course, as noted hereinabove, the control output signal 86could alternatively be utilized to control the input of a high octaneblending component such as theY reformate gasoline in order to controlthe octane rating of the finished blend to the set point value.Similarly, signal 86 could be utilized to control the input of a lowoctane blending component such as the vstraight-run gasoline.

When reference fuel is being oxidized in chamber 2, summing means 32sends a condition output signal via transmitting means 35 to an erroramplifier 36, as well as the condition output signal 26 to the displaydevice 27. The error amplifier 36 is a device which is well known in theart. The error amplifier contains a manual set point which isrepresentative of the actual known octane number of the reference fuel.Accordingly, the error amplifier receives the timing signal from timer23 via transmitting means 24 when the reference fuel is being oxi dizedwithin the combustion chamber 2. At this point then, the error amplifiercompares the condition output signal 35 with the known set point whichis correlatable with the known actual composition characteristic, suchas octane number, of the reference fuel. Thereupon the error amplifierdevelops an output signal which is a function of the difference betweenthe set point and the actual summation or condition output signal 35.

Simultaneously, the timer 23 sends an additional timing signal viatransmitting means 87 to the octane display device 27. The timing signal87 is passed to means 27 in order to lock the control signal 86 at aconstant value during that period of time when the condition outputsignal 26 is no longer indicative of the octane rating of the blendedproduct but instead is indicative of the octane rating indicated for thereference fuel. By this means, the system provides that the gasolineblending process will continue to make a gasoline blend meeting theoctane specification in response to the test sample octane value and notin response to the currently develvoped octane value of the referencefuel. During the short period of time, which is typically from 3 to 5minutes, during which the reference fuel is introduced into theapparatus, the gasoline blending process will continue to produce agasoline blend which meets the specification responsive to thecomposition characteristic and the condition output signal 26 which iscorrelatable 1with the octane rating of the test sample as of the lastmoment when the test sample was passed into the combustion chamber.

Meanwhile, the error-amplifier 36 transmits its output signal viatransmitting means 37 to a servo-amplifier 38. The servo-amplifier is adevice which is well known in the art. The servo-amplifier uponreceiving the erroramplifier output signal, reponds to the error outputsignal in order to make a correction to bring the condition outputsignal 35 -into balance with the set point contained within theerror-amplifier. Accordingly, the servo-'amplifier 38 develops an outputsignal which is portional to the erroramplifier output signal which hasbeen received. The servoamplifier is a power amplifier sending a powersignal via means 39 to a servo-motor located within signal conditioningnetwork 30. The servo-motor mechanically adjusts the signal conditioningnetwork 30 to produce an ultimate summation or condition output signal35 which is identical to the manual set point which is contained in theerror-amplifier 36. Thus the system is corrected to the known octanevalue or other base line composition characteristic of the referencefuel.

The resulting pressure output signal transmitted via line 31 thereuponbecomes directly correlatable 'with the octane number or other measuredcomposition characteristic of the reference fuel being oxidized withincombustion chamber 2. Summing means 32 thereupon develops an outputsignal 35 which passes to the error-amplifier and is therein indicatedto be in balance with the manual set point. At this juncture then, themodified condition output signal which is transmitted via means 26 tothe octane display device 27 will indicate the true octane number forthe reference fuel as corrected for combustion effects which are notindicative of the composition characteristic being determined.

When the system reaches a time when the period of isolation is over,timer 23 will switch valve 21 by means of a signal passing via line 22in order to cut out the reference fuel 20 and reintroduce the testsample 19 into the analyzer of the present invention. At this pointthen, the timer 23 sends a signal via transmitting means 24 to theerror-amplifier which will enable the system to hold the compensatingadjustment which was made in signal conditioning network 30 to balanceout the reference fuel output signal 35 with `the manual set point.Simultaneously, timer 23 passes a signal via line 87 which releases thehold which was placed upon the control output signal 86 during theisolation or reference period. In this manner then, when the test sampleof line 19 is being oxidized the modified condition output signal 26passing to the display device 27 is indicative of the compositioncharacteristic being measured, such as octane number, while beingcornpensated for component flows and temperature fluctuations and forany deviations of the reference fuel signal from the known basereference signal. Thereafter, control signal 86 will adjust controlmeans `85 in a manner sufficient to pass the lead alkyl anti-knock agentinto the blending process at a rate controlled to produce a finalgasoline blend which meets the required specification value of octanerating or any other composition characteristic being determined.

PREFERRED EMBODIMENTS Those skilled in the art will readily perceive theapparatus configuration of the present invention and the method ofoperation which have been disclosed hereinabove. Additionally, thoseskilled in the art can readily perceive the advantages of the presentinvention as disclosed hereinabove.

However, even though those skilled in the art -will easily recognize thedistinction between the terms signal conditioning means and signalconditioning network, it is deemed advantageous to define anddistinguish these terms as used herein. Referring to FIG. 1, the signalconditioning lmeans comprises the computer means 25, which contains aninternal computer program for making compensating adjustments to producethe corrected condition output signal. Referring to FIG. 2, the signalconditioning means comprises the network of elements which is, in fact,a computing system for making the compensating adjustments. Thus, thesignal conditioning networks 30, 33, 52, 58, `64 70, 76, and 82 whichare disclosed in FIG. 2, are individual elements contained Within thesignal conditioning means of that embodiment.

Furthermore, it is to be noted that the composition characteristic beingdetermined by the present invention, typically octane rating, isindicated by a condition output signal which is a function of andcorrelatable with the composition characteristic being determined.However, those skilled in the art will realize that the condition outputsignal, as illustrated by the elements 26, 35, and 84, is in tact amodified parameter output signal which in the preferred embodiment is apressure signal. Thus, when the reference fuel is passing to thecombustion chamber 2 and condition output signal 35 is compared with`the reference value signal in error-amplifier 36, the reference valuesignal is, in fact, being matched with a modified parameter signal 35.

Therefore, from the above description it may now be summarized that onepreferred embodiment of the present invention provides a lmethod forcontrolling the composition characteristic of a combustible fluidmixture produced by continuously blending a plurality of componentfluids, which comprises: (a) introducing a sample stream of said fluidmixture and a stream of oxygencontaining gas into one end of acombustion zone including an induction section maintained at elevatedtemperature; (b) partially oxidizing said sample stream in saidcombustion zone under conditions suflicient to generate and maintaintherein, a cool flame characterized by a vrelatively narrow well-definedllame front spaced from said one end; (c) sensing the position of saidllame front relative to said one end, and developing therefrom a controlsignal; (d) utilizing said control signal to adjust a combustionparameter selected from the group consisting of combustion zonepressure, induction section temperature, sample stream ilow rate, andoxygen-containing gas stream llow rate, in a manner suflicient toimmobilize said llame front relative to said one end regardless offluctuations in the composition characteristic of said sample stream;(e) sensing the adjusted parameter and developing a first parametersignal responsive to changes in said composition characteristic; (f)developing a first component signal representative of the relativeamount of a first component fluid being blended in said plurality toproduce said combustible fluid mixture; (g) passing said first parametersignal and said first component signal into signal conditioning means,and producing therefrom a first condition output signal functionallyrepresentative of the composition characteristic of said sample streamof fluid mixture, said condition output signal being indicative of saidcomposition characteristic as corrected for deviations in said parametersignal/caused by the relative amount of said first component fluid insaid combustible fluid mixture; (h) periodically isolating said samplestream from said combustion zone, and simultaneously passing a stream ofreference fuel having a known value of cornposition characteristic, intosaid zone in a manner Sullicient to continue the generation of saidimmobilized flame front; (i) sensing the adjusted parameter during theperiod of isolation and passing a second parameter signal into saidsignal conditioning means, said second parameter signal beingfunctionally representative of the apparent composition characteristicof said reference fuel; (j) comparing said second parameter signal witha reference value of parameter signal functionally corresponding to theactual known value of composition characteristic of said reference fuel;(k) adjusting said signal conditioning means in a manner suflicient toproduce a second condition output signal which is compensated to reflectthe elimination of the difference between said second parameter signaland said reference value parameter signal, and which is therebyfunctionally representative of the actual known compositioncharacteristic of said reference fuel; (l) periodically isolating saidreference fuel stream from said combustion zone while retaining thesignal conditioning adjustment of step (k), and simultaneously passingsaid fluid sample stream into said zone in a manner suflicient tomaintain said flame front, whereby said signal conditioning meansreceives a third parameter signal and a second component signalrepresentative of the relative amount of said first component fluid, andsaid signal conditioning means therefrom develops a third conditionoutput signal compensated for combustion effects not indicative ofcomposition characteristic, and said third condition output signal isthereby functionally representative of the actual compositioncharacteristic of said sample stream; and, (m) passing said thirdcondition output signal to means controlling the relative amount of asecond component fluid being blended in said plurality to produce saidcombustible fluid mixture, whereby the sample stream of fluid mixtureproduces a condition output signal functionally representative of apredetermined value of composition characteristic.

Furthermore, in its apparatus aspects, a preferred embodiment of thepresent invention resides in a blending process wherein a plurality ofcomponent fluids is continuously introduced into a blending zoneproducing a resulting combustible fluid mixture, each component fluidhaving associated therewith conduit means passing the associated fluidinto said blending zone, a control system for maintaining a compositioncharacteristic of said combustible fluid mixture at a predeterminedlevel, which comprises in combination: (a) a combustion chamber,including an induction section; (b) means for generating within saidcombustion chamber, a cool llame characterized by a relatively narrowwell-defined flame front, utilizing as fuel therefore said combustiblefluid mixture to be analyzed, said generating means including meanspassing a stream of said fluid mixture and a stream of oxidizer intosaid combustion chamber; (c) means sensing the physical position of saidllame front within said combustion chamber; (d) control means coupled tosaid position sensing means, and adapted to adjust a combustionparameter selected from the group consisting of combustion pressure,induction section temperature, fluid stream flow rate, and oxidizerstream flow rate in a manner suflcient to immobilize said flame front ina constant physical position relative to said combustion chamber; (e)means sensing the adjusted parameter and developing a parameter outputsignal, which is functionally representative of the compositioncharacteristic of said fluid stream; (f) means developing a componentsignal representative of the relative amount of a first component fluidof said plurality contained in said combustible fluid mixture; (g)signal conditioning means receiving said parameter output signal andsaid component signal; (h) condition signal generating means within saidsignal conditioning means producing a condition output signalfunctionally representative of said composition characteristic; (i)means periodically isolating said fluid stream from said flamegenerating means., and siunultaneously passing a stream of referencefuel having a known value of composition characteristic, into said flamegenerating means in a manner sufficient to continue the generation ofsaid immobilized flame front; (j) means passing to said signalconditioning means, a timing signal indicative of the passage ofreference fuel to said flame generating means; (k) comparison meanswithin said signal conidtioning means, responsive to said timing signal,adapted to compare the condition output signal generated due toreference fuel flame front with a reference value signal functionallycorresponding to the actual known value of composition characteristic ofsaid reference fuel, and therefrom developing a comparison signal; (l)adjusting means within said signal conditioning means, responsive tosaid comparison signal, and adapted to adjust said condition signalgenerating means to compensate for deviation between the conditionoutput signal .generated due to reference fuel flame front and saidreference value signal; (m) means for retaining said adjustment to saidcondition signal generating means when said isolation period is endedand said fluid stream is returned to said flame generating means inplace of said reference fuel, whereby the condition output signalgenerated by said fluid stream ame front is compensated for combustioneffects not indicative of composition characteristic, and said conditionoutput signal is thereby functionally representative of and correlatablewith the actual composition characteristic of said combustible fluidmixture; (n) means controlling the relative amount of a second componentfluid contained in said combustible fluid mixture; and, (o) meanstransmitting to said control means (m), said condition output signal,whereby said resulting combustible fluid mixture is controlled at aconstant predetermined level of combustion characteristic.

The invention claimed is:

1. Method for detecting composition characteristic of a combustiblefluid mixture produced by combining a plurality of component fluids,which compr1ses:

(a) introducing a sample stream of said fluid mixture and a stream ofoxygen-containing gas into one end of a combustion zone including aninduction section maintained at elevated temperature;

(b) partially oxidizing said sample stream in said combustion zone underconditions sufficient to generate and maintain therein, a cool flamecharacterized by a relatively narrow well-defined flame front spacedfrom said one end;

(c) sensing the position of llame front relative to said one end, anddeveloping therefrom a control signal;

(d) utilizing said control signal to adjust a combustion parameterselected from the group consisting of combustion zone pressure,induction section temperature, sample stream ow rate, andoxygen-containing gas stream flow rate, in a manner sufficient toimmobilize said flame front relative to said one end regardless offluctuations in the composition characteristic of said sample stream;

(e) sensing the adjusted parameter and developing a parameter signalresponsive to changes in said composition characteristic;

(f) developing a component signal representative of the relative amountof a first component fluid of said plurality contained in saidcombustible fluid mixture; and,

(g) passing said parameter signal and said component signal into signalconditioning means, and producing therefrom a condition output signalfunctionally representative of the composition characteristic of saidsample stream of fluid mixture, said condition output signal beingindicative of said composition characteristic as corrected fordeviations in said parameter signal caused by the relative amount ofsaid first component fluid in said combustible fluid mixture.

2. Method of claim 1 wherein said combustion zone is confined in anelevated temperature zone, a temperature selected from the groupconsisting of a temperature in said induction section and a temperaturein said elevated temperature zone is sensed and a temperature signal isdeveloped therefrom, said temperature signal is passed into said signalconditioning means, and said condition output signal is thereby renderedfunctionally representative of said composition characteristic ascorrected for temperature deviations.

3. Method of claim 1 wherein said combustible fluid mixture comprisesgasoline boiling range hydrocarbons and the detected compositioncharacteristic is octane rating.

4. Method for detecting composition characteristic of a combustible uidmixture produced by combining a plurality of component fluids, whichcomprises:

(a) introducing a sample stream of said fluid mixture and a stream ofoxygen-containing gas into one end of a combustion zone including aninduction section maintained at elevated temperature;

(b) partially oxidizing said sample stream in said combustion zone underconditions sufficient to generate and maintain therein, a cool llamecharacterized by a relatively narrow lwell-defined flame front spaced`from said one end;

(c) sensing the position of said flame front relative to said one end,and developing therefrom a control signal; t

y(d) utilizing said control signal to adjust a combustion parameterselected from the group consisting of combustion zone pressure,induction section temperature,

\ sample stream flow rate, and oxygen-containing gas stream flow rate,in a manner sufficient to immobilize said flame front relative to saidone end regardless of fluctuations in the composition characteristic ofsaid sample stream;

(e) sensing the adjusted parameter and developing a first parametersignal responsive to changes in said composition characteristic;

(f) developing a first component signal representative of the relativeamount of a first component fluid of said plurality contained in saidcombustion fluid mixture;

(g) passing said first parameter signal and said first component signalinto signal conditioning means, and producing therefrom a firstcondition output signal functionally representative of the compositioncharacteristic of said sample stream of fluid mixture, said conditionoutput signal being indicative of said composition characteristic ascorrected for deviations in said parameter signal caused by the relativeamount of said first component fluid in said combustible fluid mixture;

`(h) periodically isolating said sample stream from said combustionzone, and simultaneously passing a stream of reference fuel having alknown value of 23 composition characteristic, into said zone in amanner sufficient to continue the generation of said immobilized flamefront;

(i) sensing the adjusted parameter during the period of isolation andpassing a second parameter signal into said signal conditioning means,said second parameter signal being functionally representative of theapparent composition characteristic of said reference fuel;

(j) comparing said second parameter signal with a reference value ofparameter signal functionally corresponding to the actual known value ofcomposition characteristic of said reference fuel;

(k) adjusting said signal conditioning means in a manner sufficient toproduce a second condition output signal which is compensated to reflectthe elimination of the difference between said second parameter signaland said reference value parameter signal, and which is therebyfunctionally representative of the actual known compositioncharacteristic of said reference fuel; and,

(l) periodically isolating said reference fuel stream from saidcombustion zone while retaining the signal conditioning adjustment ofstep (k), and simultaneously passing said fluid sample stream into saidzone in a manner sufficient to maintain said llame front, whereby saidsignal conditioning means receives a third parameter signal and a secondcomponent signal representative of the relative amount of said firstcomponent fluid, and said signal conditioning means therefrom develops athird condition output signal compensated for combustion effects notindicative of composition characteristic, and said third conditionoutput signal is thereby functionally representative of the actualcomposition characteristic of said sample stream.

5. Method of claim 4 wherein said combustion zone is confined in anelevated temperature zone, a temperature selected from the groupconsisting of a temperature in said induction section and a temperaturein said elevated temperature zone is sensed and a temperature signal isdeveloped therefrom, said temperature signal is passed into said signalconditioning means, and each condition output signal is thereby renderedfunctionally representative of said composition characteristic ascorrected for temperature deviations.

i6. Method of claim 4 wherein said combustible fluid mixture comprisesgasoline boiling range hydrocarbons and the detected compositioncharacteristic is octane rating.

7. Method for controlling the composition characteristic of acombustible fluid mixture produced by continuously blending a pluralityof component fluids, which comprises:

(a) introducing a sample stream of said fluid mixture and a stream ofoxygen-containing gas into one end of a combustion zone including aninduction section maintained at elevated temperature;

(b) partially oxidizing said sample stream in said combustion zone underconditions sufficient to generate and maintain therein, a cool flamecharacterized by a relatively narrow well-defined flame front spacedfrom said one end;

l(c) sensing the position of said flame front relative to said one end,and developing therefrom a control signal;

'(d) utilizing said control signal to adjust a combustion parameterselected from the group consisting of combustion zone pressure,induction section temperature, sample stream flow rate, andoxygen-containing gas stream rflow rate, in a 'manner sufficientto'immobilize said flame front relative to said one end regardless offluctuations in the composition characteristic of said sample stream;

(e) sensing the adjusted parameter and developing a 24 first parametersignal responsive to changes in said composition characteristic;

(1f) developing a first component signal representative of the relativeamount of a first component fluid being blended in said plurality toproduce said combustible fluid mixture;

(g) passing said first parameter signal and said first component signalinto signal conditioning means, and producing therefrom a firstcondition output signal functionally representative of the compositioncharacteristic of said sample stream of fluid mixture, said conditionoutput signal being indicative of said composition characteristic ascorrected for deviations in said parameter signal caused by the relativeamount of said first component fluid in said combustible fluid mixture;

(h) periodically isolating said sample stream from said combustion zone,and simultaneously passing a stream of reference fuel having a knownvalue of composition characteristic, into said zone in a mannersuiiicient to continue the generation of said immobilized flame front;

(i) sensing the adjusted parameter during the period of isolation andpassing a second parameter signal into said signal conditioning means,said second parameter signal being functionally representative of theapparent composition characteristic of said reference fuel;

(j) comparing said second parameter signal with a reference value ofparameter signal functionally corresponding to the actual known value ofcomposition characteristic of said reference fuel;

(k) adjusting said signal conditioning means in a manner sufficient toproduce a second condition output signal which is compensated to reflectthe elimination of the difference between said second parameter signaland said reference value parameter signal, and which is therebyfunctionally representative of the actual known compositioncharacteristic of said reference fuel;

(l) periodically isolating said reference fuel stream from saidcombustion zone while retaining the signal conditioning adjustment ofstep (k), and simultaneously passing said fluid sample stream into saidzone in a manner sufficient to maintain said llame front, whereby saidsignal conditioning means receives a third parameter signal and a secondcomponent signal representative of the relative amount of said firstcomponent fluid, and said signal conditioning means therefrom develops athird condition output signal compensated for combustion effects notindicative of composition characteristic, and said third conditionoutput signal is thereby functionally representative of the actualcomposition characteristic of said sample stream; and,

I(m) passing said third condition output signal to means controlling therelative amount of a second component fluid being blended in saidplurality to produce said combustible fluid mixture, whereby the samplestream of fluid mixture produces a condition output signal functionallyrepresentative of a predetermined value of composition characteristic.

8. Method of claim 7 wherein said combustion zone is confined in anelevated temperature zone, a temperature selected from the groupconsisting of a temperature in said induction section and a temperaturein said elevated temperature zone is sensed and a temperature signal isdeveloped therefrom, said temperature signal is passed into said signalconditioning means, and each condition output signal is thereby renderedfunctionally representative of said composition characteristic ascorrected for temperature deviations.

9. Method of claim 7 wherein said second component fluid is said firstcomponent fluid.

10. Method of claim 7 wherein said combustible fluid mixture comprisesgasoline boiling range hydrocarbons 25 and the detected compositioncharacteristic is octane rating.

11. Method of claim wherein said second component uid comprises ananti-knock agent.

12. A composition analyzer for detecting a composition characteristic ofa combustible uid mixture produced by combining a plurality of componentfluids, which comprises in combination:

(a) a combustion chamber, including an induction section;

(b) means for generating within said combustion chamber, a cool amecharacterized by a relatively narrow well-defined flame front, utilizingas fuel therefor said combustible fluid mixture to be analyzed, saidgenerating means including means passing a stream of said fluid mixtureand a stream of oxidizer into said combustion chamber;

(c) means sensing the physical position of said flame front within saidcombustion chamber; I

(d) control means coupled to said position sensing means, and adapted toadjust a combustion parameter selected from the group consisting ofcombustion pressure, induction section temperature, fluid stream towrate, and oxidizer stream flow rate in a manner suicient to immobilizesaid flame front in a constant physical position relative to saidcombustion chamber;

`(e) means sensing the adjusted parameter and developing a parameteroutput signal which is functionally representative of the compositioncharacteristic of said fluid stream;

(ff) means developing a component signal representative of the relativeamount of a first component fluid of said plurality contained in saidcombustible liuid mixture; and,

(g) signal conditioning means receiving said parameter output signal andsaid component signal, and producing therefrom a condition output signalwhich is functionally representative of and correlatable with saidcomposition characteristic of the combustible uid mixture, saidcondition output signal being indicative of sad compositoncharacteristic as corrected for devations in said parameter signalcaused by the relative amount of said first component fluid in saidcombustible fluid mixture.

13. Apparatus of claim 12 wherein said control means (d) comprises meansadjusting said combustion pressure.

|14. Apparatus of claim 12 wherein said signal conditioning meanscomprises computer means.

15. Apparatus of claim 12 wherein said flame position sensing meanscomprises a pair of axially spaced temperature sensing elements.

16. Apparatus of claim 12 wherein there is provided an outer chamberencompassing said combustion chamber and confining a zone of elevatedtemperature thereinbetween, means sensing a temperature selected fromthe group consisting of a temperature in said induction section and atemperature in said elevated temperature zone, and means transmitting atemperature signal from said temperature sensing means to said signalconditioning means, whereby said condition output signal is renderedfunctionally representative of said composition characteristic ascorrected for temperature deviations.

17. A composition analyzer for detecting a composition characteristic ofa combustible fluid mixture produced by combining a plurality ofcomponent fluids which comprises in combination:

(a) a combustion chamber, including an induction section;

(b) means for generating within said combustion chamber, a cool flamecharacterized by a relatively narrow well-defined flame front, utilizingas fuel therefor said combustible uid mixture to be analyzed, saidgenerating means including means passing a stream of said fluid mixtureand a stream of oxidizer into said combustion chamber;

(c) means sensing the physical position of said flame front within saidvcombustion chamber;

(d) control means coupled to said position sensingl means, and adaptedto adjust a combustion parameter selected from the group consisting ofcombustion pressure, induction section temperature, fluid stream flowrate, and oxidizer stream flow rate in a manner sufficient to immobilizesaid ame front in a constant physical position relative to saidcombustion chamber;

(e) means sensing the adjusted parameter and developing a parameteroutput signal which is functionally representative of the compositioncharacteristic of said fluid stream;

(f) means developing a component signal representative of the relativeamount of a rst component iiuid of said plurality contained in saidcombustible fluid mixture;

(g) signal conditioning means receiving said parameter out-put signaland said component signal;

(h) condition signal generating means within said signal conditioningmeans producing a condition output signal functionally representative ofsaid composition characteristic;

(i) means periodically isolating said lHuid stream from ,said flamegenerating means, and simultaneously passing a stream of reference fuelhaving a known value of composition characteristic, into said flamegenerating means in a manner sufficient to continue the generation ofsaid immobilized flame front;

(j) means passing to said signal conditioning means,

a timing signal indicative of the passage of reference fuel to saidllame generating means;

(k) comparison means within said signal conditioning means, responsiveto said timing signal, adapted to compare the condition output signalgenerated due to reference fuel flame front with a reference Valuesignal functionally corresponding to the actual known value ofcomposition characteristic of said reference fuel, and therefromdeveloping a comparison signal;

(l) adjusting means within said signal conditioning means, responsive tosaid comparison signal, and adapted to adjust said condition signalgenerating means to compensate for deviation between the conditionoutput signal generated due to reference fuel flame front and saidreference value signal; and,

(m) means for retaining said adjustment to said condition signalgenerating means when said isolation period is ended and said fluidstream is returned to said flame generating means in place of saidreference fuel, whereby the condition output signal generated by saidfluid stream llame front is compensated for combustion effects notindicative of composition characteristic, and said condition outputsignal is thereby functionally representative of and correlatable withthe actual composition characteristic of said combustible fluid mixture.

18. Apparatus of claim 17 wherein said means (d) comprises meansadjusting said combustion pressure.

19. Apparatus of claim 17 wherein said signal conditioning meanscomprises computer means.

20. Apparatus of claim 17 lwherein said flame position sensing meanscomprises a pair of axially spaced temperature sensing elements.

21. Apparatus of claim 17 wherein there is provided an outer chamberencompassing said combustion chamber and confining a zone of elevatedtemperature thereinbetween, means sensing a temperature selected fromthe group consisting of a temperature in said induction section and atemperature in said elevated temperature zone, and means transmitting atemperature signal from said temperature sensing means to said signalconditioning means, whereby said condition output signal is renderedfunctionally representative of said composition characteristic ascorrected for temperature deviations.

22. In a blending process wherein a plurality of component fluids iscontinuously introduced into a blending zone producing a resultingcombustible fluid mixture, each component fluid having associationtherewith conduit means passing the associated iluid into said blendingzone, a control system for maintaining a composition characteristic ofsaid combustible fluid mixture at a predetermined level, which comprisesin combination:

(a) a combustion chamber, including an induction section;

(b) means for generating within said combustion chamber a cool llamecharacterized by a relatively narrow well-defined flame front, utilizingas fuel therefor said combustible lluid mixture to be analyzed, saidgenerating means including means passing a stream of said uid mixtureand a stream of oxidizer into said combustion chamber;

(c) means sensing the physical position of said flame front within saidcombustion chamber;

(d) control means coupled to said position sensing means, and adapted toadjust a combustion parameter selected from the group consisting ofcombustion pressure, induction section temperature, lluid stream ilowrate, and oxidizer stream flow rate in a manner sulcient to immobilizesaid llame front in a constant physical position relative to saidcombustion chamber;

(e) means sensing the adjusted parameter and developing a parameteroutput signal which is functionally representative of the compositioncharacteristic of said fluid stream;

(f) means developing a component signal representative of the relativeamount of a rst component iluid of said plurality contained in saidcombustible fluid mixture;

(g) signal conditioning means receiving said parameter output signal andsaid component signal;

(h) condition signal generating means `within said signal conditioningmeans producing a condition output signal functionally representative ofsaid composition characteristic;

(i) means periodically isolating said fluid stream from said llamegenerating means, and simultaneously passing a stream of reference fuelhaving a known value of composition characteristic, into said llamegenerating means in a manner sulllcient to continue the generation ofsaid immobilized flame front;

(j) means passing to said signal conditioning means, a timing signalindicative of the passage of reference fuel to said llame generatingmeans;

(k) comparison means within said signal conditioning means, responsiveto said timing signal, adapted to compare the condition output signalgenerated due to reference fuel llame front With a reference valuesignal functionally corresponding to the actual known value ofcomposition characteristic of said reference fuel, and therefromdeveloping a comparison signal;

'(1) adjusting means within said signal conditioning means, responsiveto said comparison signal, and adapted to adjust said condition signalgenerating means to compensate for deviation between the conditionoutput signal generated due to reference fuel llame front and saidreference value signal;

(m) means for retaining said adjustment to said condition signalgenerating means when said isolation period is ended and said lluidstream is returned to said llame generating means in place of saidreference fuel, whereby the condition output signal generated by saidfluid stream llame front is compensated for combustion eifects notindicative of composition characteristic, and said condition outputsignal is thereby functionally representative of and correlatable withthe actual composition characteristic of said combustible lluid mixture;

(n) means controlling the relative amount of a second component lluidcontained in said combustible iluid mixture; and

(o) means transmitting to said control means (m), said condition outputsignal, whereby said resulting combustible lluid mixture is controlledat a constant predetermined level of combustion characteristic.

23. System of claim 22 `wherein said means (f) com prises llowindicating means sensing the flow of first component fluid passing tosaid blending zone in the associated rst conduit means.

24. System of claim 22 wherein said means (m) comprises ilow controlmeans controlling the llow of second component fluid passing to saidblending zone in the associated second conduit means.

References Cited t UNITED STATES PATENTS 3,463,613 8/1969 Penske et al.23-254 3,533,746 10/1970 Fenske 23-230 MORRIS O. WOLK, Primary ExaminerR. E. SERWIN, Assistant Examiner U.S. Cl. X.R.

